Which of the following is not true with regard to anterior open bites (AOBs)?

 # Which of the following is not true with regard to anterior open bites (AOBs)? 

A. Digit sucking is commonly associated with symmetrical AOB with associated posterior cross-bite 

B. An AOB of skeletal etiology is associated with an increased Frankfort-mandibular plane angle 

C. An AOB due to digit sucking can usually resolve spontaneously in the early mixed dentition stage 

D. An AOB in permanent dentition cannot be treated with orthodontics alone

The correct answer is A. Digit sucking is commonly associated with symmetrical AOB with associated posterior cross-bite

Digit sucking often presents with an asymmetrical AOB with associated posterior cross-bite. An AOB of skeletal etiology is when the vertical component of facial growth is disproportionally greater than the horizontal growth. The patient presents with a 'long face', with an increased lower anterior facial height, pronounced antegonial notching, retrognathic chin, and reduced interincisal angle. 

A symmetrical AOB may be associated with endogenous tongue thrust.  An AOB due to digit sucking usually resolves when the patient breaks the habit in the early mixed dentition stage, but if the habit is not broken by the late mixed dentition stage a deterrent appliance may be fitted. If an AOB is present in permanent dentition it is unlikely to resolve spontaneously.  In some cases, it is possible to close mild AOBs with the orthodontic intrusion of molars. 

A 7-year-old child with multiple carious lesions is the subject of a care order. Which of the following best represents who should usually take responsibility for decisions about treatment?

 # A 7-year-old child with multiple carious lesions is the subject of a care order. Which of the following best represents who should usually take responsibility for decisions about treatment? 

A. Birth mother 

B. The child's foster parents 

C. The court 

D. The parents and local authority 

The correct answer is D. The parents and local authority.

The treating dentist must be aware of who has parental rights and responsibilities before carrying out treatment on children. This is even more important when a child is the subject of a care order, in which case the local authority has parental rights and responsibilities jointly shared with the parents. If the child is in voluntary care, parental rights, and responsibility still remain with the child's parents. It is best practice to confirm these details before starting treatment. 

For a loose complete denture relining and rebasing can be done in which of the following condition:

 # For a loose complete denture relining and rebasing can be done in which of the following condition:

A. Excessive alveolar bone loss 

B. When centric relation and centric occlusion do not coincide 

C. The patient is poor and cannot afford new dentures

D. More than 2 mm loss of alveolar bone height 

The correct answer is C.  The patient is poor and cannot afford new dentures.

Relining and rebasing Indications:

• Immediate dentures at 3 - 6 months after their original construction. 

• When the residual alveolar ridges have resorbed and the adaptation of the denture basis to the ridges is poor. 

• When patient cannot afford the cost of new dentures. 

• Geriatric or chronically ill patients 

• Centric occlusion should coincide with centric relation 

Contraindications: 

• Excessive amount of resorption 

• Abused soft tissues are present 

• Patient complains of temporomandibular joint problems 

• Dentures have poor esthetics 

• Dentures creating speech problems 

• Severe osseus undercuts exist, until surgical removal and healing occur. 

Highest incidence of maxillary extra canal is seen in which tooth:

 # Highest incidence of maxillary extra canal is seen in which tooth:

A. Maxillary first premolar

B. Maxillary first molar

C. Maxillary second molar

D. Mandibular first premolar

The correct answer is B. Maxillary first molar.

The maxillary first molar usually has three roots with a single canal located in each root except with the mesiobuccal root in which a second canal may be present. With the use of magnification devices, the incidence of this canal is as much as >90%. 

Most common variation of tooth in relation to size and mass is common in ______________ teeth.

 # Most common variation of tooth in relation to size and mass is common in ______________ teeth.

A. Mandibular and maxillary premolar

B. Maxillary canine and premolars

C. Mandibular premolar and third molar

D. Maxillary lateral incisor and third molar

The correct answer is D. Maxillary lateral incisor and third molar.

Microdontia most commonly affects maxillary lateral incisors followed by third molars. 

Macrognathia is not a feature of:

 # Macrognathia is not a feature of:

A. Paget’s disease

B. Leontiasis ossea

C. Acromegaly

D. Parry Romberg Syndrome

The correct answer is D. Parry Romberg Syndrome.

Asymmetry of the face is a feature of Rarry-Romberg syndrome. One side of the face shows relative Micrognathia. 

Parry Romberg syndrome: Genetic disorder characterized by atrophic changes of the deeper structures involving one side of the face (e.g., fat, muscle, cartilage & bone) 

Romberg syndrome: Hemifacial atrophy, progressive atrophy of soft tissue of 1/2 inch of face + contralateral Jacksonian epilepsy & trigeminal neuralgia. 

Taurodontism is characterized by:

 # Taurodontism is characterized by:

A. Hypercementosis

B. Elongated wide pulp canals and short roots

C. Obliterated pulp chambers with secondary dentin deposition

D. Rootless teeth with thin shell of enamel

The correct answer is B. Elongated wide pulp canals and short roots.

Taurodontism (Bull Teeth) is due to failure of hertwig's sheath to invaginate at the proper horizontal level. Mostly molars are involved and the body of tooth is enlarged at expense of roots resulting in rectangular teeth. The roots are short and the pulp chambers are extremely large lacking the usual constriction at cervix of tooth. It has been reported that many patients with Klinefelter syndrome exhibit taurodontism but is not constant feauture of this syndrome.